Nick Gordon, who was Bobbi Kristina Brown's longtime boyfriend, opens up about his relationship with Krissy, as he referred to her, and how she was forever changed by the death of her mother, Whitney Houston.

“She became very secluded, angry with a lot of people,” Gordon tells Dr. Phil in an exclusive interview airing Thursday. “And, another thing is she started self-mutilating. And, there was a big problem with that.”

Gordon claims that Bobbi Kristina would cut her arms and legs, and that when he spoke to her about it, she would promise never to do it again. “I would get so upset, not angry, but upset, because most people that are cutting themselves are hurt, and you could just tell that she was hurt,” he says.

WATCH: Nick Gordon Discusses Bobbi Kristina Brown's Drug Use

Gordon, who moved in with Bobbi Kristina and Houston when he was 17, says he developed a tightknit relationship with mother and daughter, and says that he became very protective of them. When Houston passed away on February 11, 2012 after being found face down in a bathtub, he felt like he let Krissy down, because he couldn’t save her mother.

“She would tell me it’s not my fault, but …” Gordon says as he sighs and hangs his head.

WATCH: Nick Gordon Reveals Details About Private Life of Whitney Houston and Bobbi Kristina Brown

Gordon claims that Bobbi Kristina also cut herself one time when her mother was alive, six months after he moved in with them. “She had to be rushed to the hospital and everything because she lost a little a little bit of blood,” he recalls.

In the video above, Dr. Phil asks Gordon, “You just think it was cutting, or do you think she was trying to kill herself?”

WATCH: Nick Gordon Addresses Claims that Whitney Houston And Daughter Bobbi Kristina Did Drugs Together

Bobbi Kristina died on July 26, 2015 at the age of 22, six months after being found clinging to life in her bathtub. On Thursday’s episode of Dr. Phil, Gordon tells his story about the night Houston died and how Bobbi Kristina reacted when he told her that her mother was dead. And, on Friday, he answers questions about Bobbi Kristina’s final moments the night before she went into a coma, and addresses accusations that he murdered her.